In addition to surgery and chemotherapy, radiation therapy is one of the three major cancer treatment methods, and it is a treatment method of killing cancer cells by irradiating radiation to a tumor volume. Generally, radiotherapy is performed by treating a tumor using ionizing radiation generated from a medical linear accelerator according to diagnosis using medical imaging devices such as a computerized tomography (CT) device, a magnetic resonance imaging (MRI) device, a positron emission tomography (PET), and the like.
In the course of radiotherapy, when radiation is delivered to the tumor volume, normal organs around the tumor volume may also be exposed to radiation. Thus, in radiotherapy, it is important to minimize radiation delivery to the normal organs around the tumor volume while delivering radiation sufficient to kill cancer cells in the tumor volume.
As radiation therapy techniques for improving accuracy and minimizing side effects, an intensity modulated radiation therapy (IMRT) technique, an image guided radiation therapy (IGRT) technique, an adaptive radiation therapy (ART) technique, and the like are known, and these techniques are continuously being developed on the basis of convergence technology. Owing to the development of these radiation therapy techniques and the complexity of a treatment planning system used for a radiation treatment plan, it is necessary to measure and verify an actual radiation dose, and to this end, various dosimeters have been developed.
Meanwhile, even in the case of head and neck radiotherapy, the surrounding organs may be generally exposed to radiation, and particularly, among the surrounding organs exposed to such radiation, a crystalline lens is one of the most sensitive organs to radiation. When a dose, which exceeds about 15% of a usual treatment prescribed dose during head and neck radiotherapy, is delivered to the crystalline lens, severe side effects such as amblyopia and a cataract may occur.
In order to minimize such side effects, it is necessarily required for a bio-dosimeter capable of measuring a dose being irradiated to a crystalline lens.
As of now, however, it is only possible to indirectly evaluate a does inside a crystalline lens by attaching a dosimeter capable of measuring a dot dose to a periphery surface of an eyeball, so that it is required to develop a technique capable of accurately measuring a dose distribution of the crystalline lens.